Timing apparatus



Oct. 23, 1956 F. J. BROCH TIMING APPARATUS 4 Sheets$heet 1 Filed Oct. 4,1954 INVENTOR FREDRlCK' J. BROCH ATTORNEY Oct. 23, 1956 F. J BROCHTIMINGVAPPARATUS 4 Sheets-Sheet 2 Filed Oct. 4, 1954 lNVE/VTOI? FREDRICKJ. BROCH WW ATTORNEY Oct. 23, 1956 J BRQCH 2,768,253

TIMING APPARATUS INVE/VTOI? .FREDRICK J. BROCH ATTORNEY F. J. BROCHTIMING APPARATUS Oct. 23,1956

4 Sheets-Sheet 4 Filed Oct. 4, 1-954 FIG.9

FIG."

INVENTOR FREDRICK J. BROCH ATTORNEY United States Patent TIMINGAPPARATUS Frederick J. Broch, Cambridge, Mass.

Application October 4, 1954, Serial No. 460,071

19 Claims. (Cl. 200-33) The present invention relates in general to theart of time delay mechanisms and more particularly concerns novelapparatus of unusual simplicity of design capable of reliably andrepetitively performing a timing function in association with varioustypes of equipment.

Although the concepts of the present invention are broadly applicablewherever interval timing is essential, electric switch-gear and inparticular time delay electric switches have been chosen as the basisfor practical illustration. In this connection, it should be observedthat time delay switches constitute a substantial fraction of thecommercial market for time delay mechanisms of all kinds.

In its most elementary form a time delay electric switch includes acontact arrangement which may either be normally open or normallyclosed, a mechanical linkage for either manually or automaticallyengaging and disengaging the switch contacts, and a timing mechanism sointerposed in the linkage that either opening or closing of thecontacts, as desired, may be made to occur at some predetermined timesubsequent to actuation.

Examination of the art will reveal that the many types of time delayelectric switches currently available commercially may be classifiedconveniently according to the extent of delay introduced by the delaymechanism, and that generally speaking the nature of the delay mechanismincorporated in each is similarly a function of the extent of the timedelay specified. For example, where delay interval required is of theorder of a fraction of a second, air or oil damped dashpot devices arein common use, and are relatively inexpensive and convenient, thoughfrequently insufliciently rugged. When the requisite time delay ismeasured in seconds, bimetallic thermal sensitive units yieldsatisfactory performance, although here the durability of such thermaldevices is often questionable.

However when minutes and even hours of delay are required, none of theaforementioned devices is capable of suitable performance, and for thisreason switches offering such lengthy delays are almost universallydriven by mechanical or electrical clockwork mechanisms.

Despite the widespread use of clockwork driven electric switches, theirdisadvantages are numerous and well known to equipment designers. Chiefamong these are high and frequently prohibitive initial cost, a completelack of ruggedness and resistance to shock or impact due to theexcessive number of delicate moving parts, and excessive size, weightand driving power. As a consequence there has existed an unfilled demandfor a time delay electric switch having sufliciently low first cost,size and weight, usable even in household electrical wiring, as, forexample, in attics and basements to prevent waste of energy due to lackof attention or forgetfulness.

The present invention contemplates as a primary object the provision ofa basically novel time delay mechanism offering compactness and designsimplicity heretofore unattainable, and which further, by virtue of itssusceptibility to mass production techniques, is universal- ICC lyapplicable to even the least expensive type of electric switchinstallations.

Broadly speaking, the time delay mechanism of the present inventionutilizes a number of mechanical elements relatively rotatable within abody of substance exhibiting specialized viscosity characteristics.

One substance found eminently suitable in actual performance is asilicone putty, commonly referred to as bouncing putty, under whichdesignation it has been distributed and sold as a novelty item. Byvirtue of the importance of this substance to the preesnt invention, itis deemed appropriate at this point to discuss in some detail the natureand properties of silicone elastic compounds, including silicone putty,without emphasis first, on the specific application thereof to thetiming function which will be described more fully below.

For reference purposes, a comprehensive technical dis cussion of theprecise properties of silicone putty and examples of the techniques ofapplication in apparatus for shock absorption, vibration minimizing,pressure equalizing, and other similar devices, an article entitledSilicone putty as an engineering material appearing in the January 1950issue of the publication Product Engineering will be found ofconsiderable assistance.

From a somewhat more functional viewpoint, the properties of siliconeputty may be sufliciently appreciated from a statement of its behaviorunder certain types of applied stress. Thus, a ball formed from a massof silicone putty will bounce from rigid surfaces with an elasticityapparently greater than gum rubber. On the other hand, if the putty ballis permitted to rest on a smooth surface, the putty will flow, simplyunder influence of the gravitational forces involved, as would a highlyviscous fluid under similar conditions. This unusual, dualcharacteristic of elasticity and liquidity of bouncing putty may befurther described as being elastic under the influence of sudden stressor impact, while fluid with respect to persistent forces above somesmall threshold value. Further amplifying this concept, if a steel ballwere dropped upon the outer surface of a cupful of silicone putty, theelastic properties would be controlling and the ball would bounce freelyon impact. On the other hand, if the ball were placed in rest on thesurface of the putty, under the influence of no other force than thatimposed by its own weight, the ball would eventually sink to the bottomof the cup.

As will become apparent from the discussion which follows, the presentinvention is primarily concerned with apparatus which benefitsmaterially from the novel properties of silicone elastic substances asabove stated and permits its utility in inexpensive timing elements. Itshould be emphasized at this point that although the discussion whichfollows will often refer to silicone putty as an active element in theinventive combination, it will be understood that any other materialexhibiting reasonably similar properties, whether compounded of siliconeor otherwise, will be capable of performing equally well. In otherwords, the use of such terminology as silicone putty or bouncing puttyshould not be considered a limitation to this ingredient alone, butrather should be considered as definitive of substances of these generalcharacteristics.

With the foregoing in view, it is another object of this invention toprovide a novel time delay mechanism which derives its operationalcharacteristics from the elastic-liquid properties of silicone putty.

A further object of this invention is to provide apparatus whichoptionally may be made to function as a substantially noiseless electricswitch or as a time controlled switch whose delay is determinable firstin the initial design and thereafter by straightforward adjustment ofmechanical components.

Another object of this invention is to provide a compact and relativelyshock-proof timing mechanism which, though not precise insofar as delayreproducibility is concerned, it is particularly well suited to use inthe numerous control arrangements where accuracy is not the criticalfactor, as, for example, in general purpose time delay electric switchesfor home and industry, time-controlled electric or mechanicalappliances, and the like.

These and other objects of the present invention will become apparentfrom the following detailed specification element which forms a part ofthe devices illustrated in the preceding figures,

Fig. 5 discloses a novel timing element operative generally as disclosedin the preceding figures, but modified for use in an alternate position,

Fig. 6 is a side view partially in section illustrating apracticalembodirnent of a time delay switch incorporating the principlesof the present invention,

Fig. 7 is a top view partially in section of the switch illustrated inFig'. 6,

Fig. 8 is a front view of elements of the switch shown in Figs. 6 and 7,a

Fig. 9 is a cross sectional view of the time delay mechanism taken alonglines 9-9 of Fig. 7,

Fig. 10 is a front view of an element of the switch combination shown inFigs. 6, 7, and 8, and including an optional feature for switch control,and

Fig. 11 is a side view partly in section of a time delay switch similarin certain respects to that shown in Fig. 6, but disclosing certainnovel variations in switch contact mechanism.

With reference now to the drawing, and more particularly to Fig. l, atime delay electric switch has been illustrated in diagrammatic form forthe purpose of demons trating the underlying concepts of this invention.In order to simplify the drawing mechanical design and constructiondetails have been omitted to the maximum extent possible; however, themanner in which the principles here disclosed may be incorporated into apractical device will be discussed below with reference to laterfigures.

Specifically in Fig. l(A)-(D) there is shown an electric switch 11 inco-operative association with a time delay element 12. Each of the viewsof Fig. 1(A)(D) show precisely the same mechanical and electricalcomponents, the various views being used for the purpose of illustratingthe sequence of events occurring in operation.

It will become apparent that the electric switch 11 need not be confinedto any one design; rather, this switch may be selected from manystandard products or may be of special design to meet needs ofparticular systems. Chosen for illustration in Fig. l is a commonsensitive snap switch such as that marketed under the trade designationMicroswitch. Switch actuation is effected by slight displacement of aspring loaded plunger 13 extending from the switch housing. In Fig. 1illustration of the contact mechanism, output terminals, and wiring hasbeen deliberately avoided since these do not in themselves form any partof the present invention. For the purpose of the present discussion itwill be assumed that the switch 11 is normally open, or off, althoughany other arrangement of a single or multiple set'of contacts is usable.

In the drawing switch 11 is schematically shown as fixed, although ithas notbeen deemed necessary to show the fixed reference frame. It willbe understood, of course, that other fixed elements are considered withrespect to the common reference.

The time delay mechanism 12 which controls the operation of electricswitch 11 is comprised essentially of a substantially sealed cylindricalhousing 15, which is rotatably operative about a smooth, relativelysmall diameter, coaxial fixed (non-rotatable) shaft 16. The housing endwalls which serve to support the housing on the shaft are not shown,particularly since the necessary bearings are formed simply by aligneddrilled holes of a diameter which permits smooth rotation on the shaft.

Directly attached to housing 15 is switch operating handle 21 by whichthe housing 15 may be angularly displaced about shaft 16. By a pair ofrigid stops, diagrammatically shown at 17 and 18, angular motion ofhousing 15 may be limited between the two terminal positions designatedin Fig. 1 as off and on, respectively.

Shaft 16 and switch 11 are fixed within the reference frame whereby theoutwardly biased switch actuating plunger 13 engages the smooth outersurface of housing 15, the latter being operative as a cam by virtue ofthe provision thereon of detent 22. In the o1 position illustrated inFig. 1(A), plunger 13 rests in detent 22.

Frictionally attached to rigid shaft 16, and freely operative androtatable within housing 15, is vane 25, the function of which will beset forth in considerable detail below. The exact configuration of vane25 is not critical. Evidently for relative freedom of movement, itsaxial dimension is less than the internal axial dimension of housing 15.The necessary frictional force between vane and shaft is achieved in theembodiment shown in Fig. 1 by use of a resilient sheet metal vane ofhairpin-like cross section having cylindrical areas arranged to gripshaft 16 in the regions 25' and 25".

To complete description of the key elements diagrammatically shown inFig. 1, housing 15 is substantially filled with a mass of bouncingsilicone putty 26 or other substance exhibiting a comparable combinationof viscous liquid and elastic properties. An air space 27, howeverslight, appears desirable.

Having set forth the general structural features, the mode of operationof the time delay electric switch illustrated in Fig. 1 will now betreated in detail.

ConsideringFig. 1(A), it will be observed that when the switch isallowed to remain in the OE position, the silicone bouncing putty willsettle to the position shown. Switch contact plunger 13 resides indetent 22 and the switch contacts are correspondingly open.

Assume now that switch handle 21 is abruptly displaced to the onposition shown in Fig. 1(B). Motion of the handle to this positioncorrespondingly rotates housing 15 about fixed shaft 16, and bydisplacement of detent 22, switch plunger 13 is depressed to turn on theelectric switch.

For an understanding of what occurs within housing 15 during thisinitial motion to the on position, one must now recall the specializedproperties of bouncing putty. In resisting sudden or rapidly appliedstress, the putty behaves as a relatively rigid mass, capable oftransmitting large forces. Because of substantial friction between themass of putty 26 and the inner surfaces of housing 15, including itsside walls, the entire mass of putty will rotate with the housing in theabrupt change from off to on. Moreover, by virtue of the fact that vane25 is embedded in the mass of putty, this rotation of the putty willcause equal rotation of the vane.

Since shaft 16 is rigidly and non-rotatably fixed in the referenceframe, both vane 25 and the mass of putty 26 slip thereon during rapidrotation of the housing. But the back resistance resulting from thefrictional engagementbetween vane and the shaft is relativelyinsignificant due to the leverage resulting from the fact that theactuating force is applied to the extended handle while the shaftdiameter is small. Further, the mass of putty 26 readily fotates aboutshaft 16, since the shaft is smooth and has relatively little exposedsurface areadue to the gripping areas of vane 25. In all, the resistanceto switch motion is somewhat less than normally encountered in commontoggle electric switches.

From an examination of Fig. 1(B) it will become apparent that the systemthere shown is in unstable equilibrium, primarily due to the weight ofeccentr-ically disposed handle 21 which introduces a continuous biastorque normally tending to rotate housing about shaft 16 to the offposition shown in Fig. 1(A). This bias torque, however, is far less thanthe torque required earlier to snap the switch from the condition shownin Fig. 1(A) to that shown in Fig. 1(B), and by itself is insufiicientto cause rapid rotation of both putty and vane about shaft 16 for returnto the position shown in Fig. 1(A). In other words, friction betweenvane and shaft prevents rapid return of housing 15 to the off positionunder forces no greater than the, bias due to the unbalanced conditionof handle 21.

However, recalling that under conditions of slight but persistentstress, bouncing putty is essentially a viscous liquid, under theinfluence of the slight but steady bias torque the housing and puttywill now slowly rotate in a counter-clockwise direction, the siliconeputty flowing as a liquid about vane 25, so that ultimately the housing15 and attached handle 21 return to the off position as shown in Fig.1(C). Here, the switch actuating button 13 has again fallen into deteut22 to turn off the electric switch.

Although again in the off condition, a noteworthy distinction betweenthe switch in Fig. 1(A) and again in Fig. 1(C) exists. As mentioned, thehousing returns to off in response to the persistent stress imposed bythe continuous bias torque. This stress, when transmitted through theputty to the vane, is insuflicient to overcome the frictional engagementbetween the vane and the shaft so that in its return to. the offposition, the vane remains stationary upon the shaft. Thus, in Fig. 1(C)the vane 25 is displaced from that in Fig. 1(A) exactly by the anglethrough which the housingyand vane turned in change from off to on.

For the purpose of further clarifying operation of this invention,reference is made to Fig. 1(D) which shows the's witch manuallydisplaced to the on position at some time subsequent to its arrival atthe off position shown in Fig. 1(C). In Fig. 1(D), rota-tion has furtherdisplaced vane 25, the displacement angle again being equal to the anglethrough which handle 21 was displaced between ofl? and on. From theposition shown in Fig. 1(D) handle 21 and attached housing will onceagain rotate slowly to the off position under the bias torque, leavingthe vane in frictional engagement with shaft 16 in the position showntherein. Thereafter, if handle 21 were again snapped to the on position,vane 25 would rotate to the position indicated by the broken line inFig. 1(D).

Thus reviewing the effect of a sequence of switch operations, each timehandle 21 is snapped to the on position, vane 25 rotates clockwise insynchronism and through an equal angle. During the return to the offposition, in completion a normal timing cycle, the switch-handle rotatescounter-clockwise while vane 25 remainsstationary. Thus, in repeatedoperation, vane 25 progresses around shaft 16 in a stepwise manner;however, it will be clear that its effect in delaying return of thehousing to the off position is nota function of angular position. Hencetime delay remains unaffected by vane orientation.

The discussion immediately above has been confined to operation of theswitch when snapped to the on position and allowed toreturn slowlyduring the delay interval to the off position under the influence of thecontinuous bias torque. But analysis will readily demonstrate thathandle 21 may be snapped from the on to the off position as readily asfrom off to on as previously discussed. For example, by simply followingthe reasoning used to explain the motion of vane 25 from its position inFig. 1(A) to that in Fig. 1(B), it is apparent that if handle 21 in Fig.1(B) were abruptly snapped to off, the entire switch mechanism includingvane 25 would return to the position shown in Fig. 1(A). In other words,although time delay is always available, the device shown in Fig. 1 maybe used as a conventional snap switch, in that at any time,notwithstanding prior operation, the switch handle may be manuallydisplaced from off to on, or from on to off. This is true not only whenhandle 21 resides in a terminal position, but at any intermediate point.Hence at any time during the interval normally required for housing 15to rotate from the position shown in Fig. 1(B) to the position shown inFig. 1(C), handle 21 may be abruptly returned to off. Conversely at anypoint in the timing cycle handle 21 may be snapped to on to renew thetiming cycle.

This discussion illustrates the unusual degree of flexibility availablewith the timing mechanism associated with the electric switch, as shownin Fig. 1. Abrupt on-off operation is at all times possible, while ifundisturbed after being placed in the on position, it will naturallyreturn to off after the predetermined timing interval.

Duration of the timing interval is a function of many factors, such asrelative dimensions of the structural members; spacing between fixed andmovable elements, bias force magnitude, frictional retarding forcesbetween relatively movable elements, and ambient temperature. It isimmediately apparent that wide delay ranges may be achieved by controlof certain of these factors in the initial design phase. Temperature, ofcourse, is a variable which enters subsequently and must therefore beconsidered from an entirely different standpoint.

The relationship between delay interval and ambient temperature, allother factors being equal, need be considered only insofar as puttyviscosity is affected by temperature change. For the silicone putty usedas a novelty item, the delay interval varies over a fairly marked range,but by and large, for most applications this may be consideredimmaterial. For instance, if an attic light were being controlled, itwould be of small consequence that the timing interval extended througha range of 30-45 minutes with seasonal variations in temperature. Thus,as noted earlier, accuracy and repro ducibility, though unavailable fromthis design, are not often functionally required. It should be pointedout, however, that some silicone compounds are noted for their viscositystability under wide temperature swings, and that the properties ofthese may be advantageously embodied here.

By appropriately controlling all factors, however, time delays rangingfrom seconds to hours may be made available. Such design fiexibility isof considerable advantage since one basic mechanism may then with minormodification be adapted to the needs of different users.

For a given switch configuration, the magnitude of the bias torque isthe factor most readily controlled. Clearly variation in the weight ofhandle 21 will result in a corresponding variation of the continuoustorque. Although not shown in Fig. l, a small spring normally biasinghandle 21 to the off position may be added to provide additional torquefor the timing cycle. Or simply, an adjustable screw extending from theend of handle 21 may be used to increase or decrease the bias. As aprecautionary note, the magnitude of the bias torque may not exceed theresistance to return motion imparted by the frictional grip between thevane and the shaft. That is to say, during the timing cycle, vane 25must remain stationary, While the putty flows as a liquid in its returnto a rest condition. An erratic timing cycle would result from slippageof vane 25.

In the. earlier discussion of the change in position betweenFig. 1(A)and Fig. 1(B), it was mentioned that frictional engagement betweenhousing and the bouncing putty resulted in rotation in unison duringabrupt motion of handle 21. Due to the relatively large internal surfacearea of housing 15, sufiicient friction is ordinarily available eventhough the interior surface is of smooth finish. However, if specificapplications require additional friction between housing and putty, theinner wall of cylindrical housing 15 may be suitably corrugated orotherwise roughened, or a number of pins may be supported on th innerhousing wall in engagement with the putty mass; caution being taken toavoid interference with operation of vane 25. On the other hand, specialprecautions are not required to minimize friction between shaft 16 andthe mass of putty due to the fact that the area of contact outside thevane is relatively small.

Friction between the outer cylindrical surface of housing 15 and switchplunger 13 should be kept low to avoid retarding rotation of housing 15under the influence of the fixed bias torque. No significant designproblem is encountered here since snap action electric switches arenormally finished with a smooth metallic plunger whose spring loading isrelatively slight due to the sensitive nature of the contact mechanism.

Fig. 1 has served as the basis for a fairly comprehensive discussion ofthe basic novel concepts underlying the present invention. Figs. 2-5disclose various alternatives which are conceptually similar, but byvirtue of mechanical departures are better applicable to meet specificneeds. Wherever possible similarity has been indicated in thatcorresponding structural elements in the various figures have beendesignated with like reference numerals.

Generallyspeaking, comparing Fig. 2 with Fig. l the functions of housing15 and shaft 16 have been interchanged. Thus, in Fig. 2 housing 15 issuitably afiixed to'the reference frame together with switch 11, whileshaft 16 is rotatable and radially supports actuating handle 21. Vaneand putty 26 remain unchanged, however, cam formed with detent 36 isattached to the shaft by a suitable radial arm for actuation of theswitch plunger 13.

Fig. 2(A) illustrates the time delay switch at rest in the on position.handle to the on position is shown in Fig. 1(B). With the shaftrotatable and housing fixed, abrupt shaft rotation will have no effectwhatsoever on putty and vane, and hence the shaft will slip relative tothese elements.

The cam 35 is fixed with respect to shaft 16 and hence rotates throughan equal angle, thereby depressing switch plunger 13 to turn on theswitch. When in the condition shown in Fig. 2(B), eccentricity of handle21 imposes a continuous counter-clockwise bias torque on the shaft,insufficient to overcome the frictional engagement between shaft andvane to cause relative rotation between the two, but sufficient toinduce gradual rotation of the shaft and the vane in unison, the puttyflowing as a viscous liquid, until the position shown in Fig. 2(C) isreached. Here cam 35 is restored to its initial position and switch isnow 0 The similarities between the devices shown in Figs. 1 and 2 areimmediately apparent. A point of distinction, however, is that since therelative functions of housing and shaft have been effectivelyinterchanged, vane 25 in Fig. 2 rotates stepwise in the oppositedirection during a sequence of timing operations.

In Fig. 3 the basic principles of this invention are embodied in adevice wherein both shaft 16 and housing '15 are rotatable. Vane 25 isrigidly rather than frictionally attached to shaft 16, while housing 15is frictionally' restrained by a leaf spring 41 which engages the smoothouter surface thereof. As in Fig. 2, a cam 35 radially attached to shaft16 is arranged to actuate switch plunger 13.. Fig. 3(A) illustrates theswitch in its nor- The effect of abruptly snapping the mally offposition. .Ifnew. handle 21 is abruptly r0 tated to on, the suddenstress is transmitted through vane 25 and putty 26 to housing 15,thereby causing equal rotation of the housing in the same direction.During this motion, housing 15 slips relative to sprin member 41.

Having arrived at the position shown in Fig. 3(B), the bias torque dueto the eccentricity of handle 21, becomes the dominant force, but isinsufficient by itself to slip housing 15 over spring member 41.However, the bias torque is sufficient to cause gradual rotation of thevane through the silicone putty which now behaves as a liquid, until theposition shown in Fig. 3(C) is reached and the switch is again off.

In this embodiment of the invention, motion of the vane is confined tothe region between the positions shown in Fig. 3(A) and Fig. 3(B),however, repeated actuation of the switch causes housing 15 to rotate instepwise fashion. This has been illustrated in Fig. 3 by designation ofa given point on the housingsurface by the letter X. In snapping theswitch to the on position, point X rotates in synchronism with handle 21as shown in Fig. 1(B). During the return timing cycle, however, point Xremains stationary while the handle returns to the off position as shownin Fig.- l(C). As in the case of preceding figures, the switch may beturned on or off while in any intermediate position, or may be allowedto follow its normal timing cycle in return from on to off.

In Figs. 13, the same basic invention has been illustrated, although therelative functions of the elements have been interchanged. Still anotherpossibility exists, in which housing is fixed as in Fig. 2, vaneattached to shaft as in Fig. 3, but where the handle is frictionallyslidable over the shaft, and carries the cam for switch actuation. Thus,when snapped to on or off, only cam and handle move, while during thetiming cycle, handle, cam, shaft, and vane move in unison through theputty.

From Figs. l-3, it may be seen that silicone putty will lie against suchbearings as are provided between shaft and housing. Normally, withclosely fitted bearing surfaces, this need not create special problems;and even with loosely fitted bearings it has been found that seepage issoon halted since in effect the putty is self-sealing. V

In Fig. 4 there is illustrated a design variation with respect to vaneand putty applicable to each of the devices shown in the precedingfigures. For the purpose of explanation, however, all basic features ofFig. 1 have been retained. Vane 25, while still generally of hairpincross section, is formed with three radially extending arms uniformlyspaced apart. The silicone compound fills only about one-third of theinterior of housing 15, and accordingly the upper surface thereof isbelow bearing 46 in the sidewall of housing 15.

Through the use of 120 spacing, there is assurance that at least one ofthe radially extending arms of the vane will at all times be immersed inthe silicone putty. Consequently. the timing cycle occurs in preciselythe manner already described in connection with Fig. l. The chiefadvantage, however, lies in the fact that at no time will the siliconebe alongside the bearings, and hence seepage is avoided entirely even iflower viscosity compounds are employed.

In Fig. 5, a time delay switch, having the characteristics of the unitdescribed in connection with Fig. 2, is shown arranged for horizontalrather than vertical operation. Fixed cylindrical housing 15 is sealedby a cover plate 52. Shaft 16 is vertically disposed in the housing axisand extends through the cover plate, resting in an internal bearing 54.Handle 21 is aflixed' to shaft 16 by set screw 55 and is consequentlyoperative in a horizontal plane between on and- 05 stops (not shown); In

motion, handle 21 actuates switch 11 by a suitable cam arrangement, thedetails of which have been omitted. Vane 25, having the general physicalcharacteristics of the vane shown in Fig. 2, is frictionally supportedon shaft 16 and immersed within a body of silicone bouncing putty 26.Since unbalance of handle 21 will not provide a restoring torque, inhorizontal operation, a small coil spring 63 has been added to rotateshaft 16 and handle 21 to the normally off position.

Step by step explanation of the operation of the time delay device shownin Fig. appears unnecessary at this point, in view of similarity to Fig.2. But it should be observed that in this embodiment, as in that shownin Fig. 4, there is complete absence of contact between the putty andthe bearing in the housing cover. Clearly the devices shown in Figs. 1and 3 may correspondingly be arranged for horizontal operation.

Referring now to Figs. 6-10, there is illustrated a practical time delayelectric switch incorporating the key concepts described with respect tothe preceding figures. The techniques disclosed in connection with Fig.2 have been selected for presentation in the figures now to bediscussed; however, it will be understood that the arrangementsdisclosed in Figs. 1 and 3-5 are equally adaptable to similar practicalswitch embodiments.

With specific reference now to Figs. 6, 7, and 8, there is shown a timedelay electric switch ideally suited as a replacement for the customarytoggle wall switch. The entire switch assembly is housed in astandardized electric wall box 71, support for the switch being providedby front bracket 72 secured to flanges extending from the open face ofwall box 71 by a pair of screws 7373. When the illustrated assembly isrecessed into a wall, face plate 75, attached to front bracket 72 byscrews 7676, conceals the mechanism contained within box 71 with theexception of operating handle 77, the latter extending out through acentrally located rectangular opening 81.

In the device shown in Figs. 6, 7, and 8, the switch contact mechanismconsists of a normally off sensitive snap switch 82 having electricalterminals in the form of screws 8383 and a molded plastic contactactuating plunger 85 spring biased to extend from the switch housing.

To those familiar with this art, it will be immediately apparent thatswitch 82 which has been arbitrarily selected for illustration is of thetype manufactured and marketed by the General Electric Company, Inc.,under the trademark Switchette. Size, weight, and currentcharacteristics combine to make this commercial switch advantageous inthis system, but as indicated below, other switch mechanisms are equallyapplicable.

A pair of mounting screws 8787 extend through the body of switch 82 tosupport it upon a generally C-shaped mounting base 91, which is in turnaffixed to side bracket 92 by a pair of supporting screws 93 and 94.Before discussing the details of this arrangement, it should be observedthat the side bracket 92 is provided with a pair of integral flanges9595 attached to the rear face of front bracket 72 by a pair of smallmachine screws 9696.

Although switch 82 is rigidly secured to switch base 91, a small degreeof adjustability exists in the relationship between switch base 91 andside bracket 92. Thus, the uppermost opening in side bracket 92 isformed as a slot 98, whereby upon loosening screw 94 from associated nut101, switch base 91 together with attached switch 82 may be pivoted to asmall degree about supporting screw 93.

Evidently, the adjustability so provided permits lateral adjustment ofplunger 85, the need for which will become apparent from the discussionwhich follows. But when the desired operating point is determined,screws 93 and 10 94 are fastened, preventing inadvertent displacement ofswitch 82 with respect to side bracket 92.

As is most clearly illustrated in Figs. 7 and 8, the face of sidebracket 92 opposite switch 82 is provided with a rigidly attachedcylindrical housing sealed by a circular end cap 106, threaded orotherwise conveniently fitted thereon.

A shaft 107 is smoothly journalled in an opening in side bracket 92 andin a recess 109 in cap 106. Within housing 105, a symmetrical section111 of shaft 107 is reduced in diameter to frictionally support vanememher 112. The shoulders formed on opposite sides of reduced diametersection 111 preclude lateral displacement of vane 112, and consequentlyprevent possible interference between vane and housing inner surface.

The cross sectional view Fig. 9 discloses the details of housing, shaftand vane. The vane previously described in connection with Fig. 4 hasbeen selected for illustration, and further, in accordance with thebasic techniques described above housing 105 is substantially filledwith silicone bouncing putty 115.

Returning to the structure on the opposite face of side bracket 92,shaft 107 is fitted with cam 121, this element being formed with aneccentric cam surface 122 in engagement with plunger 85 and with asuitably threaded opening for machine screw 123. This screw whentightened, draws together the upper and lower segments of cam 121,resulting in a firm grip between cam and shaft. Screw 123, moreover,serves to pivotally support switch handle 77.

Although the unbalanced weights of cam 121 and handle 7'7 ordinarilyapply a constant, counter-clockwise bias torque to shaft 107, as viewedin Fig. 6, additional bias torque is furnished by a small coil spring125, one end of which is hooked over cam 121 while the other end is heldsecure by the lower supporting bolt 87 for switch 82.

As shown in Fig. 6, plunger 85 engages cam surface 122 in a positionsuch that the contacts of switch 82 are in the olf condition. Whenhandle 77 is raised to the on position depicted by the broken lines 77',cam 21 is rotated clockwise and cam surface 122 drives plunger 85 inwardto close the switch contacts and complete such electrical circuits asmay be connected between terminal screws 83 and 84.

With specific reference to Figs. 7 and 9 and in view of the discussionof Fig. 2 hereinabove, it is apparent that the abrupt snapping of handle77 to on will in addition to closing switch 82 cause rotation of shaft107 while vane 112 and bouncing putty remain motionless. Having reachedthe uppermost position 77, shaft 167 will then rotate counter-clockwiseunder the influence of the constant bias torque furnished by spring 125and unbalanced weight distribution of cam 121 and handle '77. Whilereturning to oif during the delay interval, vane 112 will rotate inunison with shaft 107 through putty 115.

It may be seen that the on and off terminal positions of handle 77 aredefined by the upper and lower edges respectively of slot 13.1 in frontbracket 72. As is most clearly shown in Fig. 8, slot 131 is in the shapeof an inverted L; consequently when in its uppermost position, handle 77may be pivoted about machine screw 123 so that edge 132 prevents thenormal return to off. In other words, the switch shown in Figs. 6-9 mayreadily be locked in the on position to prevent the normal delay cycle,whenever desired In Fig. 10, as an optional feature, front bracket 72 isprovided with a pivoted stop 141 which, when secured by screw 142 in theposition shown by the solid line, will not permit locking switch handle77 in the on position. When this stop is rotated to the position shownby broken line 141', of course, advantage may again be taken of theupper slot and the switch locked on, if desired.

Fig. 11 illustrates a time delay electric switch having the generalcharacteristics of the switch above described 11 in connection withFigs. 640. The points of similarity may be readily ascertained, sincelike reference numerals have been used wherever applicable.

The significant point of departure is not in the timing mechanism whichmay, in fact, be precisely the same as illustrated in these precedingdrawings, but in the nature of the switch contact mechanism utilized.Hence no effort has been made to illustrate the mechanism behind sidebracket 92, this being essentially the same as shown in Figs. 7-9,inclusive.

The electric switch device 151 selected for illustration in Fig. 11 is awidely used sensitive snap switch sold under the trademark Microswitchby the Minneapolis-Hone well Regulator Co., Inc. As incorporated in thestructure shown in Fig. ll, however, the molded plastic cover normallyfurnished has been removed so that earn 122 bears directly against theleaf spring 153 which carries movable contact 155. Of course, a thindust cover may be provided.

While normally off as shown in Fig. ll, movable contact 155 is engagedwith fixed contact 156. When handle 77 is snapped to on, cam surface 122depresses spring member 153, causing contact 155 to snap into engagementwith fixed contact 157. In returning from the on to off, cam 122effectively releases the depressed spring member 153, so that contact155 again engages fixed contact 156.

By virtue of the direct mechanical contact existing between conductiveleaf spring 153 and cam 122, it becomes necessary to insulate handle 77.This is most effectively accomplished by molding cam 122 from a suitabledurable, but insulating substance, such as Bakelite.

Those operational characteristics of the switch shown in Fig. ll whichhave not been described are essentially the same as those discussed inconnection with Figs. 6l0. The chief advantage of the arrangement shownin Fig. 11 is that by elimination of the molded cap and leaf springoperating plunger, space requirements are materially reduced. Of course,by reduction of the number of parts, lower costs are realized.

In the preceding discussion, a division has been arbitrarily drawnbetween Figs. l5, which disclosed various basic techniques for achievinga time delay through the utilization of bouncing putty and Figs. 6-11,which served to illustrate one of these techniques in use in practicaluse. This arbitrary division of subject matter was drawn for the purposeof facilitating explanation of this invention with a minimum of figures,and should not be construed as limiting the application of any of themechanism shown in Figs. 1-5.

In illustrating practical switch embodiments, the Switchette andMicroswitch were chosen for illustration because of their widespread useand, moreover, because mass production techniques have made these aneconomical source of contact mechanisms for this purpose. mercurycontact button may be positioned on the movable element of the timedelay mechanism or otherwise actuated therefrom, to obtain onoffoperation without 'the use of snap contacts. In fact, in specializedapplications it might be desirable merely to use a sensitive movingcontact extending from the movable element of the time delay mechanismfor engagement with a complementary fixed contact. But when using acontact arrangement which is not designed for snap action, a degree ofcaution should be observed since low contact velocity inherently limitsuse to circuits where it is not required to make or break currents oflarge magnitude.

The illustration of practical switches in Figs. 61l does not ext ndbeyond the relatively small mechanism adapted for wall box use. However,nothing intrinsically limits the physical size of the time delay elementshown in Figs. 1-5. and should. it be so desired, it may be made Butwithout significant variation, the familiar V '12 sufficiently large tooperate more complex, heavy duty circuit breakers, and the like.

It is again emphasized that the application of the novel time delaymechanism herein disclosed to electric switches has been an arbitrarychoice, and that such mechanisms are capable of performing equally wellin numerous other control systems, whether they be timers in paper toweldispensers, fluid flow controls, or toys.

Finally, the physical configuration of the elements of each of the timercombinations is subject to wide variation. For example, nothingbasically requires a cylindrical housing, or cams in the shapes shown.Further, where the vane frictionally engages the operating shaft, otherless expensive devices may be substituted for the sheet metal hairpin.Thus, a resilient element, formed of rubber or'neoprene, may be piercedto fit over the shaft with the necessary frictional grip, and performthe function as described for the metal vane. The term vane whereverused will accordingly be understood to include all devices capable ofbeing used for this purpose.

In view of the fact, therefore, that numerous modifications anddepartures may now be made by those skilled in this art, the inventionherein is to be construed as limited only by the spirit and scope of theappended 7 claims.

What is claimed is:

1. Apparatus for actuating an electric switch comprising, a rotatablestructure having first and second angularly displaced terminalpositions, means imparting a continuous force normally biasing saidrotatable structure toward said first terminal position, means forming achamber associated with said rotatable structure and including asubstance exhibiting elastic properties in response to sudden forceswhile flowing gradually under application of continuous forces, saidsubstance being arranged to restrict motion of said structure to gradualrotation from said second to said first position in response solely tosaid continuous bias force without restricting the rate of rotation ofsaid structure either from said first to said second position or fromsaid second to said first position in response to sudden forces appliedthereto substantially in excess of said bias force.

2. Apparatus for actuating an electric switch comprising, first andsecond relatively rotatable elements enclosed in a body of siliconeelastic substance, said first and second elements being mutuallyarranged whereby said elements are effectively linked through saidsubstance for rotation substantially in unison in response to suddenrotation of one of said elements, said arrangement being also effectivethrough said substance in permitting gradual rotation of one of saidelements relative to theother in response to the application ofrotational forces substantially less than the aforesaid suddenrotational forces.

3. Apparatus for actuating an electric switch comprising, first andsecond relatively rotatable elements closely associated with a body ofsilicone elastic substance, means for imparting a continuous torquenormally tending to rotate said first element in one direction, saidsilicone elastic substance being effective to separate said first andsecond elements whereby said first element may be substantiallyindependently rotated in response to the application thereto ofrotational torques considerably in excess of said continuous torque ineither said one direction or the direction opposite thereto, saidsubstance being also effective to link said first and second rotatableelements for gradual rotation in unison in' said one direction whenunder the influence solely of said continuous torque.

4. Apparatus for actuating an electric switch comptising, first andsecond relatively rotatable elements closely associated with a body ofsilicone elastic substance, means for imparting a continuous torquenormally tending to rotate said first element in one direction, saidsilicone elastic substance being effective to separate said first andsecond elements whereby said first element may be substantiallyindependently rotated in response to the application thereto ofrotational torques considerably in excess of said continuous torque ineither said one direction or the direction opposite thereo', saidsubstance being also effective to link to first and second rotatableelements for gradual rotation in unison in said one direction when underthe influence solely of said continuous torque, and means limiting theextent of rotation of said first element in either of said directions.

5. Timing apparatus comprising, relatively rotatable housing and shaftelements, said shaft extending through said housing, vane means withinsaid housing frictionally engaging said shaft with predetermined force,a mass of highly viscous silicone elastic putty substantially fillingsaid housing and in contact with portions of said shaft and said vanemeans, said putty having the property of opposing sudden movementtherein of said vane means while yielding and flowing as a fluid underthe influence of slight persistent pressure of said vane means, meansfor applying a bias torque between said shaft and housing insufiicientto overcome said predetermined force and cause slippage of said vanemeans relative to said shaft but sufiicient to exert said slightpersistent pressure, whereby upon abrupt relative rotation between shaftand housing the relative position of said vane means considered withreference to said putty remains substantially unchanged while uponcessation of said abrupt rotation said bias torque causes said vanemeans gradually to flow through said putty without effect upon therelative position of vane means upon said shaft.

6. Timing apparatuseomprising, relatively rotatable shaft and housingelements, said housing containing a mass of silicone elastic putty, avane disposed for move ment within said housing and at least partiallyimmersed in said putty and frictionally engaging said shaft withpredetermined force, means for applying a continuous bias torque tendingto cause relative rotation between shaft and housing in one directionbut insutficient in magnitude to overcome said predetermined force toinduce slippage between vane and shaft, and means permitting theapplication of a rotational torque in excess of said bias for abruptlyrelatively rotating shaft and vane in said one direction or thedirection opposite thereto.

7. Timing apparatus comprising, in combination, a fixed shaft, a housingsupported upon and journalled for rotation about said shaft betweenfirst and second angularly separated terminal positions, a vanefrictionally engaging said fixed shaft with predetermined force andadapted to rotate thereon under the influence of a torque suflicient toovercome said predetermined force, said housing containing a mass ofsilicone elastic putty at least partially covering said vane, means forimparting a continuous bias torque normally tending to rotate saidhousing from said second to said first terminal direction, in onedirection relative to said shaft, and means permitting the applicationto said housing of rotative torques of greater magnitude than said biastorque for rotating said housing in either said one direction or thedirection opposite thereto, said housing, shaft and vane being arrangedwhereby, upon initial rotation of said housing to said second terminalposition, said putty, vane, and housing rotate in unison, and thereaftersaid housing, when uder the influence of said bias torque only, slowlyreturns to said first terminal position, said vane remaining fixed uponsaid shaft while said putty flows between vane and housing, and wherebythe cycle may be repeated with said vane rotating stepwise on said shaftin the direction of said initial rotation.

8. Timing apparatus as in claim 7 and including, an electric switchcontact mechanism having actuating means associated with and operativeduring predetermined movements of said housing.

9. Timing apparatus comprising, in combination, a fixed housing, a shaftextending through said housing and rotatable relative thereto betweenfirst and second angularly operated terminal positions, a vane supportedupon and frictionally engaging said shaft with predetefmined forcewithin said housing, a mass of silicone elastic putty enclosed withinsaid housing and at least partially covering said vane, means forapplying a continuous bias torque normally tending to rotate said shaftfrom said second to said first terminal position in one directionrelative to said fixed housing, and means permitting the application tosaid shaft of rotative torques in excess of said bias torque in eithersaid one direction or the direction opposite thereto, said housing,shaft, and vane being arranged whereby upon initial abrupt rotation ofsaid shaft to said second terminal position, said putty, vane, andhousing remain unmoved, and thereafter said shaft, when under theinfluence of only said bias torque, slowly rotates to said firstterminal position, said vane remaining fixed upon said shaft whilemoving through said putty, and whereby the cycle may be repeated withsaid vane rotating stepwise in the direction opposite said initialrotation.

10. Apparatus as in claim 9 and including an electric switch contactmechanism having actuating means associated with and operative duringpredetermined rotation of said shaft.

11. Timing apparatus comprising, in combination, a shaft rotatablebetween first and second angularly separated terminal positions, ahousing lfreely journalled on said shaft and containing a mass ofsilicone elastic putty, a vane rigidly affixed to said shaft within saidhousing and at least partially immersed in said putty, retarding meansfor applying a predetermined force to said housing for normallyretaining said housing in a relatively fixed position, means forapplying continuous bias torque normally tending to rotate said shaft inone direction from said second to said first terminal position, andmeans permitting the application of rotative torques to said shaft inexcess of said bias torque in either said one direction or the directionopposite thereto during which said shaft, vane, putty, and housingrotate substantially in unison, while during the application solely ofsaid continuous bias torque with said shaft in said second terminalposition, said shaft and vane rotate slowly through said putty to saidfirst terminal position with said housing fixed by said retarding means,whereby the cycle may be repeated with said housing rotating stepwise inthe direction opposite to rotation of said shaft under the influence ofsaid bias torque.

12. Apparatus as in claim 11, wherein said retarding means includes aresilient member frictionally engaging a surface of said housing.

13. Apparatus as in claim 11 and including, an electric switch contactmechanism having actuating means associated with and operative duringpredetermined rotation of said shaft.

14. Time delay apparatus comprising, a housing having a plurality ofhorizontally aligned bearings, a horizontal shaft extending through saidbearings, said housing enclosing a mass of silicone elastic puttynormally occupying a volume entirely beneath said shaft and bearings,and a vane member having a central region frictionally engaging saidshaft within said housing and formed with at least three symmetricallydisposed separated vane elements radially extending from said centralregion, and vane elements being arranged whereby at least one is at alltimes partially immersed in said silicone putty, and means for providingrelative rotation between said shaft and housing.

15. Timing apparatus for controlling the operation of an electric switchcontact mechanism having an actuating member comprising, a housinghaving a vertically disposed axis, a shaft vertically extending througha hearing in the upper portion of said housing and rotatably supportedin a bearing enclosed in the lower portion of said housing, a mass ofsilicone elastic putty within said housing and about said shaft, a vanemember frictionally fitted to said vertical shaft Within said housingand at least partially immersed within said silicone putty, meansnormally applying a bias torque tending to rotate said vertical shaft toa first terminal position, means permitting the application of rotativetorques to said vertical shaft either in the direction of said biastorque or in the direction opposite thereto, and means coupling saidshaft to said actuating member.

16. A time delay electric switch comprising, a snap action switchcontact mechanism having an actuating member, a bracket supporting saidswitch contact mech anism, a shaft rotatably extending through saidbracket, a switch operating handle affixed to said shaft and formedwitha cam surface arranged to cause displacement of said actuatingmember in response to handle movement between first and second terminalpositions, a housing affixed to said bracket and enclosing a portion ofsaid shaft, said housing being filled at least in part with siliconeelastic putty, vane means frictionally supported upon said shaft withinsaid housing and at least partially immersed in said silicone putty, andmeans normally applying a rotative torque for continuously biasing saidhandle and shaft to said first terminal position, said housing, shaft,vane, and handle cam surface being arranged whereby upon initial abruptmotion of said handle to said second terminal position, said putty,vane, and housing remain unmoved, and said switch is snapped, andthereafter, said shaft and handle when under the influence of only saidbias torque slowly rotate to said first terminal position to return saidswitch to its initial condition, said vane remaining fixed upon saidshaft while moving through said putty, and whereby the cycle may berepeated with said vane rotating stepwise in the direction opposite saidinitial rotation.

17. Apparatus as in claim 16 and including, means associated with saidsecond terminal position for locking said handle thereat to precludemotion thereof under the influence of said bias torque.

18. Apparatus as in claim 16, wherein said handle is pivotally securedto and arranged for rotation in a plane substantially parallel to theaxis of said shaft, a front bracket formed with an inverted L shapedopening 19. A time delay electric switch comprising, a switchrnechanismincluding within an enclosure a snap action leaf spring supporting amovable contact and at least one complementary fixed contact, a bracketsupportingv said switch enclosure, a shaft journalled in said bracket, aswitch handle affixed to said shaft and formed with a cam extending intosaid switch enclosure and engaging said leaf spring, a timing elementsecured to said bracket and including a housing enclosing a portion ofsaid shaft and substantially filled with silicone elastic putty, and avane frictionally engaging said shaft Within said housing and at leastpartially immersed in said putty, said cam being arranged to actuatesaid leaf spring to cause engagement and disengagement of saidcomplementary contacts in motion of said handle between first and secondterminal positions.

References Cited in the file of this patent UNITED STATES PATENTS

